She'll know very soon! The 31-year-old pregnant star told Us Weekly Thursday at the launch of the Jessica Simpson Girls collection in New York that she and fiance, Eric Johnson, will find out the gender of their baby on Monday.

So why aren't Simpson and her NFL beau going to wait until their baby's born to find out its sex? "I like to plan things out," Simpson told Us. "It'll be good to know what colors to make the nursery. I'm obsessed with thinking about what it's going to look like."

The "Fashion Star" mentor told Us the best part of being pregnant is "just knowing that [Eric] and I created something inside of me is so crazy to think about. We love each other so much, and knowing that I love this baby inside of me is so amazing."